Michael Williamson wrote in message ...
running with scissors wrote:
Michael Williamson wrote in message ...

John Gilmer wrote:



SIlly question but ...

Why would "they" pressurize the aircraft to sea level? Why not some
compromise "pressure" like that equivalent to, say, 6,000 or 8,000 feet?


Typically, they start at whatever the local pressure altitude
happens to be (which of course may or may not be sea level, depending
on where you happen to have the chamber). Also, I've never
experienced in any altitude chamber ride a rapid REcompression
down to sea level- it strikes me as a good way to have sinus
or ear problems.

Mike



nope. when the doors on an aircraft are shut the pressure is ambient.
thats it. when bleed air pressures the cabin its noramlly to about
8000ft.

While the final (steady state) pressure of the aircraft
(as determined by the cabin pressurization controller) will end
up at its cruise setting, the aircraft is pressurized from
takeoff and the cabin altitude will typically climb slowly
toward its set value (about 8,000' in this case) rather than
follow ambient- the pressurization system is indeed pressurizing
the aircraft its initial field elevation up to the cruise
pressurization setting.

In addition, my above response was poorly worded and I actually
was commenting on the pressurization of the altitude chamber- which
begins at whatever the ambient pressure happens to be. My bad for
not reading the question closely enough.

Mike


ditto, my bad for not reading closely. although you used the words
cabin pressurization, you did use the word chamber too !